Hey Everyone!
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ATTN: LINK SPOILER
http://www.sounddomain.com/ride/2387835--------------------------------------------------
I forgot to update my alias to reflect my real name so my previous post got deleted. Some of you may recognize my name as one of the first to build the LAB horn back over four years ago. In the interim I've devoted my time to earning my BS in electrical engineering and gotten significantly into circuit design and layout. That first LAB horn I built is now for sale on the LAB Marketplace as I prepare for graduate school.
During my last semester of senior year I got this bug to build a horn subwoofer for my car. It's a 1999 Subaru Outback and the strange roof contour seemed like an ideal place for an extended horn. The actual volume for the horn was dictated by the size of the rear area behind the back seats. A first version was drawn up utilizing the maximum volume for everything which meant losing the space for the spare tire. Having a spare tire floating around your car takes up a lot of space.
All the flares were simulated using HornResp which is an excellent program but it's accuracy is going to be questionable in such a strange environment. Since it's kind of loading into two corners, the passengers are essentially within the horn. Now I have heard before that the pressure modes would cause awful sound without the doors open or something strange but I beg to differ. The first version has been one of the best sounding automotive subwoofers I have ever heard. It had a 38L rear volume which caused the driver to unload at too low of an input level so I decided to build a second version after graduation.
Version 2 of the subwoofer was built with a 15L rear volume which causes a little bit of a "boomy" sound to the bass. That was tuned out with two 12db/octave filters. One is centered at 80Hz and one around 100Hz. I really like my subwoofer to only cover the low bass range so that it is harder to localize. In the next week sometime, I plan on improving the rear volume to 25L while still ensuring that the spare tire sits comfortably below the sub.
I have built a small page with the CAD models and simulations as well as construction and final pictures on sounddomain.
http://www.sounddomain.com/ride/2387835 Soon I will add some new pictures of the final box so that it makes a bit more sense. I hope with the pictures available you can figure out how it was built and give me some feedback.
I would really like to hear what you guys think and any suggestions you all have. If anyone else has attempted something like this, please let me know. Thanks for all the inspiration and advice and I look forward to hearing from you all again about this crazy project!
Cheers!
A.J. Cooper